Eulbul Sa-mul

Eulbul Sa-mul was a Goguryeo cadet who fought in the Goguryeo-Tang War of 645 AD. He was the last surviving member of the Eulbul clan after the disastrous Battle of Mt. Jupil, and, while he was initially sent by Yeon Gaesomun to assassinate the rival general Yang Manchun, he ultimately joined Yang during the Siege of Ansi.

Biography
Eulbul Sa-mul was born in Ansi, the eldest son of the Eulbul clan, and he joined the Goguryeo army as a cadet during its war with Tang China in 645 AD. He was the only member of the Eulbul clan to survive the Battle of Mt. Jupil, after which he was assigned by General Yeon Gaesomun to assassinate General Yang Manchun, whom he branded a traitor for refusing to support his dictatorship or assist his army at Mt. Jupil. Eulbul was sent to Ansi Fortress to assassinate Yang, but Yang and his right-hand man Choo Soo-ji ambushed Eulbul and his entourage on the road to Ansi while pretending to be farmers with a stuck wagon. They killed the other soldiers and spared Eulbul, deciding to take him to Ansi for interrogation. Yang correctly predicted that Eulbul was originally from Ansi and that he had been sent by Yang to assassinate him, but Eulbul said that he wished to share the fortress' fate. Yang then introduced him to the fortress' commanders and decided to make Eulbul his standard-bearer during the battle, conferring a great honor upon him as they prepared to defend Ansi from the Chinese. Eulbul fought bravely in defense of the fortress, although he confronted Yang about his lack of loyalty to Yeon and considered carrying out his mission before Yang told him that it was his responsibility to defend the fortress, and that Ansi was his priority. Eulbul went on to save Yang's life after Yang was struck by a javelin to the arm, killing a Chinese officer who was about to finish off the wounded general. He later executed Yang's former finacee, a Korean medium who had warned the Chinese about Pa-so's cavalry ambush on the Chinese camp in order to help them kill Pa-so and thus gain a chance at surrendering in the future. He later broke through the siege lines to head to Pyongyang, where he begged Yeon for reinforcements, arguing that Yang was not a traitor, but a man of Goguryeo who was defending the country. Ultimately, Eulbul convinced Yeon and his army to relieve the Siege of Ansi, winning the day and saving Korea.